A known earlier method for the preparation of dihydrojasmone and its homologues is found in the Journal of Organic Chemistry, 29, 904, (1964), Sisido et al. This route involves the reaction of ethyl gamma, gamma-dialkyl glycidates with sodium malonate to obtain lactonic intermediates, followed by hydrolysis of the lactone diesters formed in the first step to give diacids, decarboxylation of the diacids to paraconic acid, then conversion to the dihydrojasmone analogue by action of polyphosphoric acid on the paraconic acid.
The present invention is an improvement on the above prior art method in that it avoids the use of the glycidyl compound. This class of compounds is known for its toxic nature (see Sax, "Dangerous Properties of Industrial Materials", 5th Edition, (1974) and its carcinogenic possibilities. Accordingly, such materials pose a safety problem in commercial production. This problem is avoided according to the present invention by starting with nitroalkanes and acrylic esters, or substituted gamma nitropentanoic acids.